Tensioning and reversal of web without rollers



Feb. 6, 1968 P. w. JAcoBsEN TENSIONING AND REVERSAL 0F WEB WITHOUT ROLLERS 3 Sheets-Sheet 1 Filed May 19, 1965 mf@ 'y ATTORNEYS Feb. 6, 1968 P. w. JAcoBsEN 3,357,039

TENSIONING AND REVERSAL OF WEB WITHOUT ROLLERS Filed May 19, 1965 9 F. 7 s n. Mw 2 w t 7 2 .Z k d, 2 0 n 2 O /ff 7,/ f /ff /f/ f 7 4 5 /o f 2 /H/ H 2 2 ,.rv a O O .0 H 2C H 2 5 a m 7 n 2 H M d/ f O D@ /3 O OZ y I/l n. 1%, D v/ WM// M O 22 2 Z O O5 .U Ufa H 4 H n f/f/f/fh/f/ff//ff/ /f/M/f//f/f/ k 7 Y 2 0 2 2 w 5 7 a MM5 L 2 MMM 11| 55M 7. MMM C T www ATTORNEYS Feb. 6, 1968 P. w. JACOBSEN TENSIONING AND REVERSAL OF WEB WITHOUT ROLLERS Filed May 19, 1965 3 Sheets-$heet INVENTOR. BWL W Jacaasf/V ATTORNEYS f HY La United States Patent O 3,367,039 'IENSINING AND REVERSAL (BF WEB WITHGUT RULLERS Paul W. Jacobsen, Kiel, Wis., assigner to H. G.

Weber and Company, Inc., Kiel, Wis., a corporation of Wisconsin Filed May 19, 1965, Ser. No. 457,038 12 Claims. (Cl. 3ft- 52) ABSTRACT F THE DISCLOSURE Drying apparatus for Webs in which the web passes through a drying chamber in the form of festoons along opposite sides of forced air drying and return elements. The web is trained over and downwardly along parallel spaced endless mesh belts and the drying chamber is maintained at a higher pressure at its top portion than its bottom portion to maintain the web in engagement with the belts by the differential in pressure between the top and bottom of the chamber. rIhe lowering or elevating of the bights or the festoons which may be caused by differences in speeds of the endless belts is compensated for by sensing devices sensing the position of the loop and changing the speeds of the required belts to maintain the bights uniform throughout the drying chamber.

This invention relates generally to a web treatment apparatus and more specifically to a high speed web dryer system.

It is a primary object of the present invention to provide a high speed web treatment apparatus which has a relatively short longitudinal dimension in comparison with the length of the web accommodated in the treatment zone.

Another object of the present invention is to provide a high speed web treatment apparatus which accomplishes proper web tensioning and/ or web reversal without the use of pinch rollers.

Yet another object of the present invention is to provide a new and improved web dryer capable of removing unwanted moisture from a moving continuous web, and/or for drying inks or other substances which are applied to a web in a minimum time and space.

A feature of the present invention resides in the provision of a web drying apparatus whereby heated air is applied to a series of festoons in a moving continuous web.

A further feature of the present invention relates to a drying apparatus with two chambers of different pressure, the chambers being separated by means of a festooned web passing through the dryer at high speed.

Other objects and features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention, itself, however, both as to the organization, manner of construction, and method of operation, together with futher advantages and objects thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings, in which:

FIGURE l is a somewhat diagrammatic vertical sectional view of a web dryer apparatus in accordance with the present invention;

FIGURE f2 is a diagrammatic view illustrating an automatic control circuit for association with the web dryer apparatus of FIGURE l;

FIGURE 3 is a fragmentary transverse sectional view taken substantially along line III-III of FIGURE 1 with certain parts removed in order to show the adjustable mounting for the bafes;

FIGURE 4 is a fragmentary View of the Side wall of ICC a drying unit, showing the alternately arranged intake and exhaust passageways;

FIGURE 5 is an enlarged fragmentary sectional view of the upper portion of a drying unit constructed in accordance with the principles of the present invention;

FIGURE 6 is an enlarged fragmentary sectional view of the upper portion of a return unit; and

FIGURE 7 is a diagrammatic vertical sectional view of an alternate embodiment of the web dryer apparatus.

In the following description a web treatment apparatus will be described in detail wherein there is established a static differential of air pressure between opposite sides of a web to provide a series of loops or festoons in the web. In one embodiment the position of the loop or festoon is sensed to accordingly vary the speed of the web driving means. In a second embodiment the festoons are tapered, with their positions being determined by the pressure maintained on the free ends of the tapered festoons.

Shown in FIGURE l is a web drying apparatus designated generally by reference numeral 10. A dryer housing 11, preferably of refractory material, has an input passage 13 and an output passage 14 for receiving a moving continuous web 15 therethrough. A forced air heating unit 16 is connected to the dryer 11 by means of a duct 17. The duct 17 is provided with an adjustable valve 18 for controlling the rate of air flow into the dryer 11. This in turn controls the static pressure within the upper portion of the dryer 11. A second duct 19 has one end thereof connected to the heating unit 16. The duct 19 passes through an upper wall 2G of the dryer 11 and then branches out into a plurality of smaller ducts 21 through 27 provided with control valves 28 through 34, respectively. A duct portion 19a, which supplies air to the individual ducts 21-23, extends from the duct 19 toward the inlet opening 13 in a plane substantially through the longitudinal center of the dryer 11. A duct portion 19]), which supplies air to the individual ducts 25-27, extends from the duct 19 toward the outlet opening 14 in a plane substantially through the center of the dryer 11. The duct 24 extends directly downward from the duct 19 between the ducts 19a and 19h and is in the same plane as the ducts 19a and 19h. The air ducts 21-27 have connected thereto drying units 38 through 44, respectively, by means of a manifold which is described hereinafter.

The dryer 11 is provided with an air return system having a main duct 46 which may be connected to the heating unit 16. Also shown connected to the heating unit 16 is an air return duct 47 which has the other end thereof connected to an opening 48 located near the bottom of the dryer 11 as seen in FIGURE 1. The main air return duct 46 has a plurality of ducts S41 through 56 which pass through the upper Wall 2li and are connected to the respective drying units 35S-44 as indicated for drying unit 39 in FIGURE l.

The drying units 38-44 are constructed in substantially the same manner and an understanding of each of the drying units can be had from a detailed description of the drying units 38 and 39 which have been shown in section in FIGURE 1. To better illustrate the connection of the air ducts 21 through 27 to the drying units 38 through 44, respectively, the drying unit 38 and a portion of the duct 21 are sectioned through a plane passing through the air exhaust ducts and the drying unit 39 is sectioned through a plane passing laterally adjacent the air outlet passages shown in the dryer unit 38 to show a plurality of air intake slots. With reference to the drying unit 3S, the duct 21 passes through an upper wail 35 of the drying unit and is connected to a triangularly shaped manifold 36 within the drying unit, The manifold 36 extends laterally from the point of connection of the duct 21 across the drying unit 38 to supply hot air to a plurality of parallel spaced vertical hot air passages 61.

On each side of the drying unit 3S is a plurality of rows of horizontally elongated rectangular hot air exhaust ducts 60 which extend from the outer surface of the drying unit 38 to a main hot air inlet passage 61. The passage 61 is in direct communication with the hot air duct 21 through the manifold 36. Also in each side wall of each drying unit is a plurality of rows of horizontally elongated rectangular return air intake slots as indicated at 62 in unit 39. The slots 62 communicate with the interior of the drying units such as indicated at 63 for unit 39. This space is in direct communication with the air return duct which is connected to an opening in a top wall 37 of the dryer unit 39. In the preferred embodiment of the present invention, the air return ducts 50 through 56 pass through the upper wall 20 of the dryer 11 in a plane parallel to the branches of ducts 19a and 19b and immediately adjacent thereto. Referring to the dryer unit 39, a space 57 located between the inside of the upper wall 37 and the top of a manif-old 58 serves as an air return manifold for the air which is received through the slots 62. The rectangular exhaust ducts 60 and the rectangular intake slots 62 are arranged in respective vertical planes parallel to the plane of FIGURE ll and offset from each other. Dryer 38 is sectioned on a vertical plane through the centers of ducts 60, and dryer 39 is sectioned on a vertical plane through the centers of intake slots 62. The offset between the vertical planes through the centers of ducts 60 and slots 62 may be less than the horizontal dimensions thereof so that the opposite ends of ducts 60 are vertically aligned with and overlap the ends of slots 62.

A pair of movable side battle plates 65 are adjustably carried within the dryer at the respective opposite sides of the path of web 15. The side plates each have a central generally rectangular aperture 65a corresponding to the cross section of the dryer units 38-44 and along which the baffles are adjustably movable. For purposes of clarity, only one of the side baffle plates 65 and a portion of another is shown in FIGURE 1. Each of the plates 65 preferably Ahas four adjusting screws 66 connected therewith which may extend through threaded bosses which are secured to the associated wall of the dryer 11. The plates 65 are shaped to almost completely iill the space between a corresponding pair of wire belts and the drying unit disposed therebetween. Should it be necessary to adjust the lateral position of the side plates 65 to accommodate a different width web the adjusting screws 66 are turned in the desired direction.

One of a cooperating pair of side plates 65 is provided with a pair of light sending elements 67, and the other of the pair of plates 65 is provided with a pair of light receiving elements 68. In the preferred embodiment of the present invention the light sending elements 67 and the light receiving elements 68 are positioned so that the light beam between corresponding elements is maintained at an angle with respect to the edgewise dimension of the loop portions a-15Jt of the web 15 thereby increasing the effectiveness of the edge of the web 15 in interrupting a light beam between cooperating pairs of sending and receiving elements 67 and 68. However, it will be understood that the light sending elements and the light receiving elements can be operated in a substantially parallel arrangement with respect to the width of the web 15.

Located within the dryer 11 is a plurality of continuous wire belts 70-77. Each of the wire belts 70-77 is wrapped about a pair of mounting rollers. That is, the belt 70 is wrapped about a pair of rollers 80 and 81, the belt 71 is wrapped about a pair of rollers 82 and S3, the belt 72 is wrapped about a pair of rollers 84 and 85, the belt 73 is wrapped about a pair of rollers 86 and 87, the belt 74 is wrapped about a pair of rollers 88 and 89, the belt 75 is wrapped about a pair of rollers 90 and 91, the belt 76 is wrapped about a pair of rollers 92 and 93 and the belt 77 is wrapped about a pair of rollers 94 and 95. A plurality of backup idler rollers 99 serve to support each of the wire belts 70-77. Each of the wire belts 70-77 is driven independently of the others by a suitable differential drive system connected to the shaft of one of the mounting rollers at one of the opposite ends of the loop formed by the wire belt. By way of example, shafts 160 and 101 are driven by a separate differential drive system.

The side baffle plates 65 are preferably conformably shaped to the space between the wire belts 7(3-77 and the inside upper portion of the dryer 11. The top portion 65h of each baffle plate 65 extends from the Verticalcenter of one wire belt to thevvertical center of an adjacent wire belt as indicated in FIGURE l. The side baflie plates 65 and the portion of the web 15 which passes through the dryer 11 divide the dryer into two chambers 11a and 11b. During operation of the dryer the pressure within the chamber 11a is maintained at a greater value than the pressure within the chamber 11b.

Alternatively, the side bafiie plates which are mounted on either side of the web path may be of unitary construction. A pushbutton may be provided to energize a gear head motor, not shown, to position each of the two onepiece side bafe plates to a predetermined position.

After the web 15 passes through the inlet opening 13, the web is directed downwardly along the wire belt 70 and then upwardly along the wire belt 71. The web 15 then passes over the wire belt 71 and down the other side. Then the web 15 is carried upwardly by the wire belt 72. It can be seen therefore that the web 15 passes through the dryer 11 by alternately changing its direction of travel as the web passes over successive wire belts 70-77 to form a series of festoons within the dryer 11. The lower loop portions 15a-15g of the festoons formed in the web 15 are maintained within predetermined limits between the associated light sending element 67 and the light receiving elements 68 near the lower end of the dryer 11.

Shown in FIGURE 2 is a somewhat diagrammatic representation of a differential drive system which can be used in conjunction with the web transport and dryer apparatus of FIGURE 1. Although only two differential drive and control systems are shown, it will be understood that a differential drive and control system is provided to control each of the wire belts 70-77. By way of example, a differential drive unit 130 has an output shaft 131 coupled directly to the shaft 100 of roller 81 of FIGURE 1. Connected to the differential drive is a suitable speed adjusting means which is shown as a resistor 133. The resistor 133 can be adjusted either manually or by means of an automatic control which is indicated by the dotted line 134. The automatic control 134 is rendered operative to either increase or decrease the speed 0f the differential drive 130 in accordance with a light signal sensed by a light receiver unit 135. The light receiver unit 135 is provided with a pair of light receiving elements 137 and 138 which receive light energy fromI a corresponding pair of light sending units 139 and 140 of a light source 141. The light energy emitted from the element 139 is indicated by a dotted line 143 while the light energy from the element 140 is indicated by a dotted line 144. Connected to the light receiver 135 is a pair of indicating lamps 146 and 147 to give a visual indication of the condition of the loop portion 15a of the web 15 passing between the light beams 143 and 144. By way of example, when the loop 15a rises to interrupt the light beam 143 the light receiver 135 will cause the indicating lamp 146 to be illuminated, thereby giving a visual indication that the speed of the differential drive 130 should be increased. On the other hand, should the loop 15a fall and interrupt the light beam 144, the light receiver 135 will cause the indicating lamp 147 to be illuminated, thereby giving a visual indication that the speed of the differential drive 130 should be decreased.

A second differential drive unit 150 has an output shaft 151 coupled directly to the shaft 101 of the roller 83 of FIGURE 1. Connected to the differential drive unit 150 is a suitable speed adjusting means which is shown as a resistor 153. The resistor 153 can be adjusted either manually or by means of an automatic control which is indicated Iby the dotted line 154. The automatic control 154 is rendered operative to either increase or decrease the speed of the differential drive 150 in accordance with the iight signal received by a light receiver unit 155. The light receiver unit 155 is provided with a pair of light receiving elements 157 and 158 which receive light energy from a corresponding pair of light sending units 159 and 160 of a light source 161. The path of the light energy emitted from the element 159 is indicated by a dotted line 163, while the path of the light energy emitted from the elements 160 is indicated by a dotted line 164. Connected to the light receiver 155 is a pair of indicating lamps 166 and 167 to give visual indication of the condition of the loop b of the web 15 passing between the light beams 163 and 164. By way of example, when the loop 15b rises to interrupt the light beam 163, the light receiver 155 will cause the indicating lamp 166 to be illuminated, thereby giving a visual indication that the speed of the differential drive 150 should be increased. On the other hand, should the loop 15b fall and interrupt the light beam 164, the light receiver 155 will cause the indicating lamp 167 to be illuminated, thereby giving a visual indication that the speed of the differential drive 150 should be decreased.

TO sense the position of the loops 15a and 15b, the light beams 143-144 and 163154 are arranged to be interrupted by the edge of the moving web 15. The edgewise dimension of the moving web 15 is comparatively small. Therefore, to increase the effectiveness of the edge dimension of the web the light beams pass athwart the web 15 at an angle suflicient to provide adequate interruption of the light beam to produce the necessary corrective signal in the light receivers 135 and 155. The preferred physical location of the sending units such as 139 and 159 is indicated as the upper one of the pair of light sending units 67 on the baille 65, and the preferred physical location of the sending units such as 140 and 160 is indicated as the lower one of the pair of light sending units `67 on the battle 65 as seen in FIGURE 1. The preferred physical location of the receiving units such as 137 and 157 is indicated as the upper one of the pair of light receiving units 68 on the bale 65, and the preferred physical location of the light receiving units such as 138 and 158 is indicated as the lower one of the pair of light receiving units 68 on the baille 65 as seen in FIGURE l.

Shown in FIGURE 3 is an alternate embodiment of web drying apparatus designated generally by reference numeral 200. The web dryer apparatus 200 is provided with a dryer housing 202 which has an input opening 203 and an output opening 204 for receiving a moving web 205 as it passes through the dryer 202. At the top of the dryer 202, as seen in FIGURE 3, is duct 208 for delivering a supply of heated air into the dryer. The duct 208 has two passages 207 and 210 separated by a baille 213. The passage 207 is provided with a control valve 214 and the passage 210 is provided with a control valve 217 for controlling the `llow of air through the respective passage. Located in opposing side walls 209 of the dryer 202 are a pair of rectangular slots 211 and 212. As seen in FIG- URE 3 the slots 211 and 212 in the side wall 209 may be arranged substantially aligned with similar slots in the opposite side Wall. Also located in each of the side walls 209 are a pair of rectangular openings 215, 216 and 216a which serve as outlets for the heated air Within the housing 202.

Carried within the housing 202 is a continuous wire belt 218 which is wrapped about a plurality of rollers 220 through 226. One or more of the rollers 220-226 may be driven by a suitable variable speed drive. The portion of the wire belt 218 which engages the web 205 is provided with a plurality of back-up idler rollers 228 to help 6 support the wire belt 218 and the web 205. A reel 201, which delivers the web 205 to the dryer 202, is provided with a constant tension means 206 and assists to prevent the end portion 205a of the web 205 `from engaging the reversing roller 222.

The web 205 is carried by a supply reel 201 for delivery to the dryer 202. At the output of the dryer 202 the web 205 is wound on a take-up-reel 219 which is driven by a positive drive 227. The spacing between the side walls 209 may be substantially equal to the width of the web 205. One or both of the side walls 209 may be adjusted to change the width of the dryer 209 to substantially equal the width of the web 205. However, this is not to be construed in a limiting sense, the dryer 202 may be provided with bales similar to the bales as shown in FIGURE l. Preferably, the wire belt 218 is permeable. Therefore, the side walls 209 of the dryer 202, the bale 213 of the duct 208 and the web 205 divide the dryer 202 into three chambers 202a, 202b and 202C which may have different. levels of pressure.

Summary of operation As shown in FIGURE l, the web 15 enters the dryer 11 through an opening 13 and passes over the top of the moving wire belt and down one side thereof. The web 15 is then brought in contact with the moving wire belt 71 and carried thereby up one side of the belt 71 and then down the other side thereof. The web 15 is then brought in contact with the wire belt 72 and carried up one side thereof and down the other side. It can be seen therefore, that as the web 15 passes through the dryer 11 it will successively engage the wire belts 70-77 in such a manner as to form a series of festoons in the web. The festoons in the web 15 each have a loop or free end 15a-15g which is not in contact with the associated wire belts 70-77. The loop 15a-15g of the festoons formed by the web 15 are maintained within a predetermined range of positions by means of a pair of light sending elements 67 and a corresponding pair of light receiving elements 68 which have light beams associated therewith passing athwart the web 15 on either side of the loop.

By way of example, the web 15 forms the free end 15) as the web passes down one side of the wire belt 75 and then up one side of the wire belt 76. Should the speed of the web 15 which is traveling down the wire belt 75 be greater' than the speed of the web 15 which is traveling up the wire belt 76, the amount of material which forms the free end 15f will be increased, thereby causing the free end 15]c to extend downward between the wire belts 75 and 76, as shown in FIGURE 1. This action will cause the light beam between the lower light sending element 67 and the lower light receiving element 68 to be interrupted thereby causing a corresponding light receiving unit to give a visual indication that the speed of the wire belt 75 should be decreased relative to the speed of the wire belt 76. On the other hand, should the web which is traveling along the wire belt 76 be traveling at a greater speed than the web which is traveling along the wire belt 75, the free end 15]c will be raised thereby interrupting the light beam emitted from the upper light sending element 67 which, in turn, will cause the corresponding light receiving unit 68 to give the necessary visual indication that either the speed of the wire belt 75 should be increased or the speed of the wire belt 76 should be decreased. It will be understood that the operation of the light sending and receiving elements is substantially the same for other loops or free ends 15a-15e and 15g.

A supply of heated air under pressure is delivered to one surface of the web 15 by means of a plurality of heating elements 38-44. Only the heating units 38 and 39 are shown in detail to provide a better understanding of the present invention. As shown in the heating element 38, heated air from the duct 21 is delivered to the 'channel 61 through the manifold 36 located within the heating element 38. The heated air within the channel 61 passes through the plurality of exhaust ducts 60 and impinges upon the surface of the web 15. The quantity or rate of flow of the pressurized heated air is regulated by means of the valve 28 located within the duct 21. It may be noted that the heated air which impinges upon the surface of the moving web will aid in maintaining the web 15 in contact with the wire belts 70 and 71. After the heated air has impinged upon the surface of the moving web 15, the air, which has picked up moisture from the surface of the web, is then returned to the heating unit 38 through the plurality of rectangular slots 62, as shown in the heating unit 39. The air within the heating unit 39 is delivered to the air return duct 51 through the space 57 which serves an an air return manifold within the heating unit.

A portion of the pressurized heated air which is delivered to the dryer 11 may pass between the openings which are located between the baffle plate 65 and an adjacent component and enter the low pressure chamber 11b. To remove this air from the chamber 11b of the dryer 11, the airreturn duct 47 is connected between the opening 48 and an air inlet of the heating unit 16. This will maintain the chamber 11b at a substantially reduced pressure relative to the pressure in the chamber 11a. That is, the pressure of the heated air applied to the web 15 by the heating elements 38-44 is greater than the pressure of the air which is removed from the chamber 11b. Furthermore, the pressure differential between the chambers 11a and 11b help maintain the web 15 in firm contact with the transporting portion of the wire belts.

Referring to the embodiment of FIGURE 3, the web 205 enters lthe dryer 202 through the opening 203 and then passes over the top of the moving continuous wire belt 218. As seen in FIGURE 3, the web 205 travels downwardly along the wire belt 218 thereby forming a festoon which has a loop or free end 205e. The web 205 continues to travel along the wire belt 218 thereby forming a second festoon which has a free end 205i). A pressure differential on the web 205 is maintained at a predetermined value by supplying heated air under pressure through the passages 207 and 210 of the duct 208 and by removing moist air via the openings 215 and 216 which are located in the side walls 209 of the dryer 202, as seen in FIGURE 3. The amount of heated air which is delivered to the chambers 202b and 202e is controlled by the valves 207 and 210 respectively and the amount of moist air which is removed from the chamber 202e is controlled by the slots 215 and 216.

In the preferred embodiment of the present invention, the festoons formed in the web 205 are tapered as they approach the -bottom of the throat between the transporting portions of the wire belt 218. The unsupported portion of the web 205 is decreased as the loops 205e and 205b fall deeper between the wire belt 218. As the loops 205e and 20517 fall deeper between the wire belt 218, the total frictional force between the web and thewire belt is increased thereby preventing slippage of the web 205. Also, as the loops 205e and 205b fall deeper between the wire belt 218, the effective area of the loop upon which the heated air exerts its pressure is decreased and the effective force applied to the loops 205e and 205k is decreased. Therefore, with this progressive reduction of surface area of the loops 2055i and 205b of the web 205 a progressively greater unit pressure is required on the loops 205a and 205b to force the loops further between the wire belt 218. Because of this pressure and surface area gradient, a specific pressure differential on each surface of the web 205 will represent a specific position of the loops 205a and 205b. The vents 211 and 212 which are located adjacent the loops 205m and 205b respectively are provided to compensate for poorly regulated air pressure or pressure surges to prevent the loops from descending too far between the wire belt 218 and engage the rollers 222 and 224 respectively.

If the web 205 has a low tensile strength, the portion of the wire belt 218 which is in driving engagement with the web may be parallel with the other rather than tapered. In this case, the vents 211 and 212 are required to control the position of the loops 205a and 205b.v

It will be understood that the features of the embodiment of FIGURES l and 2 may be applied to the embodiment of FIGURE 3 and vice versa. For example, drying units such as 38 in FIGURE l may also be provided in FIGURE 3 within the chambers 202!) and 202C. The exterior walls cf the drying units may taper so as to be parallel to the path of the web 205 in the `two chambers. The drying units may extend downwardly to near the tops of slots 211 and 212, for example.

Although the drawings and specification present a detailed disclosure of preferred embodiments of the present invention, it is to be understood that the invention is not limited to the specific form disclosed, but covers all modifications, changes, and alternative construction falling within the scope of the principles taught by the invention.

I declare also that the systems of FIGURE 1 and FIGURE 3 make an excellent web impregnator. Each system may ybe used as a web impregnator only, or a combination of web drier and impregnator. The amount of impregnation can be controlled by the amount of differential air pressure imposed across the web.

I claim as my invention:

1. In a web dryer,

a dryer housing having a web input station and u web output station accommodating a web to be dried to pass into said housing at one end thereof and out from said housing at the opposite end thereof,

a series of vertically extending drying units spaced along said housing,

each drying unit having alternately arranged heated air outlet slots and moist air return slots,

a forced air heating unit connected with said drying unit to supply air to be ejected through said outlet slots,

a main return unit connected with said drying unit to return spent air through said return slots,

means training the web entering and leaving said drying housing in theform of a plurality of vertically extending festoons between the web input station and the web output station and extending along opposite sides of each drying unit and having a bight disposed beneath each drying unit,

and an air outlet from said drying housing adjacent the bottom thereof, withdrawing air from the bottom of said housing and establishing a lower pressure on the outer sides of said festoons than on the in sides thereof, to maintain the web into engagement with said means training and advancing the web along said housing.

2. The structure of claim 1,

wherein the means training and advancing the web from the input station through the output station and training the web in the form of festoons comprise individual vertically extending endless wire belts extending along opposite sides of said drying units,

and wherein means are provided for individually driving said wire belts at proportionate rates of speed to maintain the bights of the festoons at substantially the same elevation throughout the length of the dryer housing 3. The structure of claim 2,

wherein baffles extend between said wire belts at opposite ends of the festoons and confine the air within said festoons to provide a high pressure region forcing the festoons into engagement with said wire belts.

4. The structure of claim 3,

wherein means are provided for mounting said bullies within said dryer housing for adjustable movement toward and from the festoon web.

5. The structure of claim 4,

wherein sensing means are carried by said battles at opposite ends of the festoons and sense the position of the free end of the festoon and wherein the sensing means eiects the controls of the operation of the means for individually driving each of said wire belts.

6. ,In a web dryer,

a closed dryer housing having a web input at one end thereof and a web output at the opposite end thereof, through which the web enters and leaves said dryer housing,

at least one continuous wire mesh belt within said housing trained from the input to the output end of said housing in the form of a plurality of vertically extending loops and forming the web into a series of festoons conforming to the loops of said wire belt and having free lower end portions spaced above the loops of said belt,

heated air inlets leading into said drying chamber into the space between said loops and directing heated air under pressure into said festoons and maintaining the web into engagement with the insides of the loops of said Wire belt,

return outlets leading from said chamber from the spaces between said loops and drawing moist air from said drying chamber and establishing a differential in pressure between the spaces within said festoons and the spaces outside of said festoons to maintain the web in contact with said wire during travel of the web from the input to the output end of said housing.

7. The structure of claim 6,

wherein drive means at the output end of said housing draw the web from the input to the output end of said housing at the speed of travel of said endless wire belts,

and wherein tension means at the input end of said housing maintain tension on the web during travel thereof from the input to the output end of said housing.

8. The structure of claim 6,

wherein air vents are provided in the region of the bights ofthe festoons of the web, to regulate the positions of the bights of the festoons relative to the loops of said wire mesh screen.

9. The structure of claim 6,

wherein the wire belt is arranged in the form of a plurality of vertically extending tapered loops converging from the upper to the lower ends thereof, and forming the web into a series of tapered festoons conforming to the tapered loops of said wire belts.

10. The structure of claim 9,

wherein air vents are provided in the region of the bights of the festoons of the web to regulate the positions of the bights of the festoons of the web relative to the loops of said wire mesh screen.

11. A web transport and dryer apparatus comprising:

a dryer housing having a web input station and a web output station for receiving the web passing through said dryer housing;

a source of pressurized heated air;

yduct means connected between said source of pressurized heated air and said dryer housing;

lsaid duct means having a plurality of outlet ports 1ocated within said dryer housing;

va plurality of continuous wire belts in said drying housing arranged in such a manner as to form in the web a series of festoons;

heat delivery means between each of said continuous wire belts and connected to a corresponding one of said outlet ports of said duct me ms tor receiving pressurized heated air and delivering it to a substantial area of the web travelling on the wire belts adjacent each of said heat delivery means;

said heat delivery means having a plurality of output ports for delivering heated air to the web and a plurality of inlet ports for removing moist air from within the dryer;

adjusting means carried about each of said heat delivery means for adjusting the width of the path followed by the web passing through said dryer;

sensing means carried by each of said adjusting means for sensing the position of the free end of the festoon formed by the web; and

drive means connected to each of the said wire belts for driving the corresponding wire belts at a predetermined speed.

12. A web transport and dryer apparatus comprising:

a dryer housing having a web input station and a web output station for receiving the web passing through said dryer housing;

a source of pressurized heated air;

duct 4means connected between said source of pressurized heated air and said dryer housing;

said duet means having a plurality of outlet ports located within said dryer housing;

`a plurality of continuous wire belts in said dryer arranged in such a manner as to form in the web a series of festoons each having a substantially free end;

heat delivery means between each of said continuous wire belts and connected to a corresponding one of said outlet ports of said duct means for receiving pressurized heated air and delivering the air to a substantial area of the web travelling on the wire belt adjacent each of said heat delivery means;

ladjusting means carried about each of said heat delivery means for adjusting the width of the path followed by the web passing lthrough said dryer housing;

a pressurized chamber formed within said dryer housing and defined substantially by one inner wall of said dryer housing, the inner surface of each of said adjusting means, and one surface of the web passing through said dryer housing;

a chamber of lesser pressurization formed within said dryer housing and defined substantially by the remaining inner walls of said dryer housing, the outer surface of each of said adjusting means, and the other surface of the web passing through said dryer hous- 111g;

air return means connected to the chamber of lesser pressurization within said dryer housing for removing moist air therefrom; and

drive means connected to each of said wire belts for driving the corresponding wire belt at a predetermined speed.

References Cited UNITED STATES PATENTS 505,117 9/1893 Meissner 34-159 X 1,996,020 3/1935 Hurxthal 34--159 X 2,303,476 12/1942 Kornegg 34-159 2,462,380 2/1949 Gautreau 34-l56 X 2,986,912 6/1961 Richeson et al. 68-5 3,012,335 12/1961 Allander et al. 34-155 3,074,261 1/1963 Wilcox 34-159 X 3,089,252 5/1963 Daane et al. 34-114 3,177,749 4/ 1965 Best et al. 226-42 X 3,231,985 2/1966 Smith 34--157 X 3,277,305 10/ 1966 Anderman 226--28 FREDERICK L. MATTESON, JR., Primary Examiner.

A. D. HERMANN, Assistant Examiner. 

